Comtech EF Data CDM-570L Installation And Operation Manual page 314

CDM-570/570L Satellite Modem with Optional IP Module
IP Module - CLI and Telnet Operation
Transmit Encrypt Enabled
Receive Decrypt Enabled
Transmit Key 1 - 8
Receive Key 1 - 8
Save Parameters
Exit
A 24 Byte [192-bit] 3xDES key is actually a combination of 3 single DES keys of 8
Bytes [64-bits]. The CLI will display the Key with a space separating the Key into 3
sections. In the screen capture above, Transmit Key 1 is displayed as:
IMPORTANT
Consider the first section as Key1A, the second as Key1B, and the third as Key1C.
Data is first encrypted with Key1A and then decrypted with Key1B and again
encrypted with Key1C. So if a user specifies all the three Keys the same, (like 48
'1's OR all the characters in DES key the same) the cumulative effect of 3xDES is just
a single DES. When data is first encrypted with Key1A and decrypted with Key1B we
get back the original data and then when encrypted with Key1C results in a total effect
of single DES key.
Because of this, the user is required to enter unique 64-bit keys. If any 2 sections
of the Key match, the
enter
Also, The Least Significant bit of each byte in a 24 Byte [192-bit] 3xDES key is
reserved for the DES Algorithm for parity. Entries of 1, 3, 5, 7, 9, B, D, or F will have all
the corresponding bit positions masked. So a Key entry of:
Read Displays feature status. This field is updated via the
Only Features Configuration menu.
If Transmit Encrypt is disabled, then all traffic
processed by the
clear regardless of the 3xDES encryption key
specified in the Route table.
Read Displays feature status. This field updates via the
Only Features Configuration menu.
1 These 3xDES keys are used to encrypt traffic being
through sent over the Satellite Interface.
8
The key is entered in HEX (48 digits max)
A These 3xDES keys are used to decrypt traffic being
through received from the Satellite Interface.
H
The key is entered in HEX (48 digits max)
S This option allows a user to save the current
configuration to permanent storage. This configuration
will be restored on each successive power cycle.
X This option allows a user to exit the current menu and
return to its parent menu.
2222222222222222
IP M
odule will respond
1111111133333333 5555555577777777 99999999BBBBBBBB
1010101032323232 5454545476767676 98989898BABABABA
17–14
IP M
odule will be transmitted in the
4444444444444444
Invalid Key - Please Re-
becomes
Revision 4
MN/CDM570L.IOM
6666666666666666